Hot-air heating unit



Oct. 30, 1951 J. c. FRANK 2,573,004

HOT-AIR HEATING UNIT Filed May 20, 1949 2 SHEETS-SHEET 2 7 III zillll 2 INVENTOR.

Patented Oct. 3.0, 1951 UNITED STATES PATENT OFFICE HOT-AIR HEATING UNIT John 0. Frank, Naperville, Ill.

Application May 20, 1949, Serial No. 94,387

8 Claims. (01. 237-16) The present invention pertains to an improved hot air heating boiler or related type of unit in which the air to be circulated through a space or system to be heated (or cooled, as the case may be) is subjected to heat action in association with a body of water or other liquid in which tubes or pipes circulating said air are immersed.

Existing water heating boilers for hot air heating systems are usually characterized by a relatively involved and expensive system for circulating the respective heating media, such as Water and air, involving coils, radiators and the like. Moreover, their efficiency is not particularly high. Furthermore, the air heated thereby and circulated throughout a dwelling or other space or system to be heated is quite dry and not con ducive to healthy living conditions.

The present invention affords a heating unit which is adapted to supply a copious quantity of heated air at proper humidity, providing a very enjoyable, mildly moist heating of the space in question. It accomplishes this without recourse to the aforesaid coils, radiators and the like, relying on an arrangement of simple, straight tubular hot air circulating and hot water circulating pipes of standard, readily available type associated with one another and with certain space enclosing, sealed shells in an improved fashion. The arrangement is such that the most direct and efiicient transfer of heat takes place between the original products of combustion of the unit, the intermediate Water heating medium and the ultimate hot air heating medium at all times. In brief, the unit relies for its efficiency of operation upon the highly simplified and efficient method of circulation of said media within the unit. The construction is such that the air heated can be brought to desired temperature in a relatively short space of time. Furthermore, due to the fact that the hot air circulating tubes thereof are completely immersed in intermediate liquid heating medium, the hold-over period in which a substantial amount of heat continues to be transferred from said intermediate medium to the hot air, after termination of operation of the burner, is relatively protracted, thereby economizing on the cost of operation of said burner.

Although particularly devised for air heating purposes, it will be recognized by those skilled in the art that the present unit is also well adapted for use as an air conditioning and cooling unit, by the mere substitution of a refrigerant fluid for the normal water medium, and in making other simple changes which will be obvious to those skilled in the art.

It is thus an object of the invention to provide an improved air heating boiler unit which operates at high efficiency in the initial transfer of heat from the products of combustion of the burner or fire pot of the unit to an intermediate liquid heat transfer medium exposed to the heat of said combustion products, and the subsequent transfer of heat from said liquid medium to the ultimate space heating medium, such as air.

A further object is to provide a unit of the type described in which the respective heat transfers are accomplished by means of an improved arrangement of concentric sealed casings or shells and air and water tubes disposed in novel relation to said burner or fire pot and to each other.

Another object of the invention is to provide such a hot air heating unit or boiler which is of improved compactness and efiiciency, which affords a copious supply of mild, moist air to be circulated in a space to be heated, and which is of low cost of production since it eliminates the relatively expensive coil and radiation provisions normally associated with units of this general character, obtaining the requisite heat transfer capacity by the improved arrangement of tubes and sealed shells, which is referred to in the preceding paragraph.

A still further object is to provide a heating unit of the above type characterized by a direct circulation of the ultimate heating medium, i. e.,

air, in efiicient, heat transfer relation t an intermediate, liquid heating medium, i. e., water, by means of a plurality of air tubes of standard type disposed in circular order, which tubes are completely immersed in said intermediate heat ing medium, and in which said intermediate heating medium is in turn directly circulated in efficient, heat transfer relation to the original source of heat, 1. e., the products of combustion of the burner of the unit, by means of a plurality of standard, concentrically arranged Water tubes positioned to traverse a space in which they are disposed in immediate, direct heat transfer relation to said products of combustion.

Still more specifically, an object of the invention is to provide an improved, highly compact and structurally simplified, efiicient and inexpensive boiler type heating unit, particularly devised for installation in a hot air heating system, which unit is characterized by a novel arrangement of a multiplicity of vertically extending hot air heating tubes disposed in a generally circular, multiple tier arrangement, said tubes being concentrio with a plurality of vertically extending Water tubes, also disposed in a circular arrangement,

and by a pair of concentric sheet metal, sealed shells housing said respective sets of tubes, the

innermost of said shells enclosing a central fire box space or combustion chamber throughout which products of combustion are circulated in direct heat transfer relation to the water tubes, said water tubes vertically traversing said chamber, and the other of which shells defines an annular water chamber receiving said vertically extending air tubes, there being an external, annular hot air manifold surrounding said water chamber from which air heated in said air tubes issues to the space or system ultimately to be heated.

A still further specific object is to provide a boiler of the foregoing description, in which said hot air tubes are of an improved, internally spiral character for a more efficient, thorough and uniform heat transfer from the intermediate liquid medium surrounding the same to the air or like medium traversing the interior thereof.

The foregoing statements are indicative in a general way of the nature of the invention, but other and more specific objects will be apparent to those skilled in the art upon a full understanding of the construction and operation of the device.

A single embodiment of the invention is presented herein for purpose of illustration, but it will be appreciated that the invention is susceptible of incorporation in other modified forms coming equally within the scope of the appended claims. 1

In the drawings,

Fig. 1 is a view in longitudinal vertical section through the hot air heating boiler unit of the present invention, illustrating the general arrangement of the combustion chamber in which the fire box or other burner means of the unit is disposed, the water circulating tubes vertically traversing said chamber, the air circulating tubes in heat transfer relation to a volume of water circulated in said first named tubes, the air intake manifold to the air tubes and the external air discharge manifold;

Fig. 2 is a view in transverse, horizontal cross section along a line corresponding to line 2-2 of Fig. 1; and

Fig. 3 is an enlarged fragmentary view in vertical cross section through one of the hot air cir- 'culating tubes of the unit, illustrating the pro vision for accomplishing the most efiioient transfer of heat through the wall thereof.

Referring to the drawings, the reference numeral Ill generally designates the boiler or heating unit of the present invention. In order to simplify the disclosure, all external insulating provisions such as would normally be present in a unit of this character have been eliminated. It should also be understood that the drawings are more or less diagrammatic in character.

The reference numeral I l designates a fire pot, preferably of a suitable heat resistant ceramic material the side wall of which is apertured at 12 for association with a burner or other combustion unit of any desired character. For the purpose of illustration the laterally extending duct l3 which is receivable in the aperture l2, in sealed relation thereto, may be considered to represent a portion of an oil burner, or gas burner. The invention is not limited in this respect; solid fuel may be burned in the fire pot ll by providing a conventional type of grate structure therein, to which coal or coke is introduced by means of a stoker or the like equivalent of the combui iQn.

unit [3. The fire box is of generally cylindrical outline, being internally, concentric with the various shell, chamber and casing components as well as the two annular sets or banks of tubular circulating pipes to be described, as illustrated in Fig. 2 of the drawing. The fire pot is appropriately supported in rigid relation to the remainder of the unit, for example, by opposed, conventionally illustrated supporting and clamping irons i4. These are mounted on a suitable fixed support in a manner which it is not deemed necessary to illustrate or describe in detail.

The fire pot II is concentrically surrounded by a sealed, sheet metal combustion chamber or shell l5 of cylindrical cross section which is covered at its top and bottom by the respective circular end plates Hi, I'd. Plates l6, l! are sealed in liquid tight relation to the shell i5, and are each provided with a series of circular tube receiving apertures arranged in circumferentially spaced order concentric with the shell it. The respective apertures of the end plate it are vertically aligned with those of the plate ii.

A plurality of water circulating tubes 18 in the form of standard lengths of pipe are arranged to traverse the combustion chamber or shell 15 in the vertical direction, parallel to the axis of the unit 10, these tubes being circumferentially spaced and disposed in accordance with the circumferential spacing and disposition of the tube receiving apertures in end plates l3 and ll. At opposite ends thereof the water tubes it are aligned with said apertures and sealed to the respective end plates Iii, H in watertight relation thereto. Naturally, the tubes it are chosen of a material which is resistant to heating or corrosive damage by the hot gaseous products of combustion in the chamber it, which gases are circulated in immediate heat transfer relation thereto. The tubes must also resist corrosive damage by the intermediate heating medium, i. e., water, which is circulated within said tubes. The same is true of the combustion chamber it.

A further, generally cylindrical shell it is disposed in concentric relation to the combustion chamber shell l5, in outwardly spaced relation thereto. The shell i9 is of greater axial length than shell [5, overlapping both ends of the latter, and closed at said opposite ends by the circular top and bottom end plates 29, El, respectively. These are sealed in liquidtight relation to said shell l9. Like the plates is, ii, the end plates 20, 2| are provided with a plurality of circular apertures for the reception of the air circulating pipes or tubes 22.

As illustrated in Fig. 2, the tubes 22 are circumferentially spaced from one another in two concentric tiers which are in close radial adjacency to one another. The tubes in each tier are likewise disposed in close circumferential relation to one another. In order to improve the circulation of the water heating medium relative to the hot air tubes 22, I provide a cylindrical, vertically extending, sheet metal baflle 23 between the respective tiers of air tubes 22, said baille being substantially coextensive in axial length with the internal, combustion chamber shell it, as illustrated in Fig. l. The baiile 23 may be appropriately supported in a fashion which will be-' come apparent as the description proceeds.

The tubes 22 are tightly sealed to the respec-- tive top and bottom end plates 29, 2i at the openings in said plates receiving the tubes, and the sealed external and internal shells I9, 15 thusserve to constitute an annular water circulating hamber or manifold. Tubes 22' are fully imnersed in the water circulated in said chamber by lvater tubes I8, for an efficient, rapid transfer of seat from the water heating medium to the air which is circulated within said tubes 22.

The shell I9 may be supported by the opposite end extensions 24, 25 of certain of the air tubes 22, which extensions project above the upper end plate 20 and below the lower end plate 2I of the water shell I9. The lower extensions 25 support said shell and the components of the unit within the same and the upper extensions 24 support the further structure of the unit to be described. The inner combustion chamber shell I5 is supported on the lower end plate 2| of the external water shell I9 by means of an appropriate angle iron base 2?. Suitable side braces may be employed to hold these shells in predetermined lateral, concentric, displacement resisting relation to one another.

An outer casing of sheet metal construction, generally designated 28, surrounds the water shell I9 in radially spaced relation thereto and a circular base plate 29 is applied to the lower margin of casing 28, being sealed in airtight relation thereto. Said plate 29 supports the bottom extensions 25 of the air tubes 22, which serve to sustain the above described structure. The casing 28 and its end plate 29 thus provide an air circulating manifold 30 surrounding the sides and bottom of the Water shell I9 in spaced relation thereto. At its upper margin this manifold is sealed off by the lateral extension 28 of the upper end plate 20 of the water shell I 9.

An upper, air intake manifold 32 is applied to the unit above said water shell end plate 28. This air manifold is constituted by a hollow cylindrical housing or cap 33 suitably sealed around its lower margin to the plate 20, in airtight relation thereto. The upper extensions 24 of air tube 22 project through the intake manifold 32 for supporting engagement with its constituent housing as illustrated in Fig. 1. These upper tube extensions are laterally apertured at 35 for the admission of incoming air from intake manifold 32, and the lower extensions 25 of said air tubes are also provided with apertures 35 for the egress of air traversing the tubes into the air circulating manifold 55. An air supply fitting 3i communicates with the manifold 32 in air sealing relation to the housing 33 of the latter. Air or other medium to be heated or conditioned is fed through this fitting 31, preferably by means of a fan.

Referring to Fig. 1, the reference numeral 49 generally designates an open expansion tank which is communicated with the interior of the water shell I9 opening through the center of the top plate 2!) of the latter. The cooling water tank, designated II, may be incorporated with the unit III in the event it is to be used for air conditioning purposes. This unit is communicated with the water shell through the bottom end plate 2! of the latter. Its use, as well as that of the expansion tank 40, is optional.

The respective shells I5, I 9 and casing 28 are laterally apertured to receive a gas discharge duct 52, through which the products of combustion pass from the combustion chamber I5 to the stack. Said shells and casing are also preferably apertured at a more elevated point for the reception of a sheet metal housing 43 which is equipped with a transparent, rectangular sight glass as through which the condition within the combus tion chamber may be observed from the exterior of the unit.

Referring to Fig. 3, I have found that the heat transfer operation between the intermediate liquid heating medium and the ultimate hot air heating medium is improved and expedited by the provision of a spiral formation or ribbing 45, or equivalent roughening or interruption of the internal surface of the air tubes 22. This produces a degree of turbulence in the flowing air stream which is conducive to more efficient transfer of heating units from the tube wall to said stream.

In operation, air supplied. to the intake manifold 32 through the intake fitting 31 travels downwardly through the air tubes 22, entering the majority of the same through their open ends at upper plates 20, and through the apertures 35 in the extension 24 of the remainder of the tubes which project upwardly of said plate. The cir culatory path of the air is indicated by the broken lines in Fig. 1. It pases downwardly through the tubes 22 into the manifold 30, exiting through the bottom end plate 2! of the water shell, or through the side openings 36 in the lower extensions 25 of those tubes 22 which project beneath the plate 2|. The air then circulates upwardly and about the sides of a cylindrical shell i9, after which it exits through an elevated side opening 46 in said shell and is circulated through an appropriate duct system throughout the space to be heated.

In traversing the tubes 22, of which there are a multiplicity, as illustrated in Fig. 2, the air is heated to desired degree by Water surrounding the same within the shell I9, the water being circulated in said shell by the water tubes I8, as indicated by solid arrows in Fig. 1. The baffle 23 causes a circulation from the tubes I3 above upper end plate I 6 of the combustion chamber shell I 5, thence outwardly beyond the cylindrical baffle 23, downwardly between water shell I9 and said bafile, thence upwardly beneath the bafile and between the same and the internal, combustion chamber shell I 5, a portion of the circulating water returning upwardly through the water tubes I8 at their openings in the lower end plate I? of the combustion chamber. So circulating, the water is efficiently heated by the hot products of combustion in the combustion chamber.

Iclaim:

l. A direct circulation, air conditioning structure comprising an internal sealed shell, means to heat the interior of said shell, a plurality of liquid circulating tubes traversin the interior of said shell in sealed relation thereto and opening externally of the opposite ends of the latter, a plurality of air circulating tubes disposed externally of said shell, a second sealed shell surrounding said air tubes and the open ends of said liquid tubes to define a liquid receiving chamber coacting with said liquid tubes in the continuous circulating of liquid in heat transfer relation to the exterior of said air tubes, an air discharge manifold, said air tubes opening at one end thereof to said manifold, and an air intake manifold sealed from said discharge manifold, the air tubes opening at the opposite end thereof to said intake manifold.

2. A direct circulation, air conditioning structure comprising an internal sealed shell, means to heat the interior of said shell, a plurality of liquid circulating tubes traversing the interior of said shell in sealed relation thereto and opening externally of the opposite ends of the latter, a plurality of air circulating tubes disposed externally of said shell, a second sealed shell suring said second shell in spaced relation to the side wall and one end thereof and coacting therewith to define a concentric air discharge manifold, said air tubes opening to said manifold through and in sealed relation to said end of said second shell, means defining an air intake manifold above said second shell and sealed from said discharge manifold, the air tubes opening through the opposite end of said second shell to said intake manifold, certain of said air tubes extending beyond said ends of said second shell into said respective manifolds to brace said shell relative to said casing and manifold defining means, and means to supply air to said intake manifold, said casing having an air discharge opening communicating said discharge manifold with the exterior of said boiler structure.

JOHN C. FRANK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

